The present invention relates in general to integrated circuit packaging, and more particularly to an improved ball grid array package with radio frequency shielding capability.
High performance integrated circuit (IC) packages are well known in the art. Improvements in IC packages are driven by industry demands for increased thermal and electrical performance and decreased size and cost of manufacture.
In general, array packaging such as Plastic Ball Grid Array (PBGA) packages provide a high density of interconnects relative to the surface area of the package. Typical PBGA packages include a substrate and a semiconductor die attached to the substrate by a die adhesive. Gold wire bonds electrically connect the die to metal traces on the substrate and the wire bonds and die are encapsulated in a molding material. Solder balls are disposed on the bottom surface of the substrate for signal transfer.
Conventional molding materials are plastic and serve to encapsulate, protect and provide support for the semiconductor die and wire bonds. While such structures have achieved considerable use, these packages fail to provide shielding, which is desirable for certain applications such as radio frequency (RF) applications. The plastic molding materials are substantially transparent to radio frequency electromagnetic radiation and consequently radio frequency interference signals or electromagnetic interference signals are permitted to enter and escape from the IC package.
With increasing performance and package density demands, the interference signals emitted from IC packages is also increasing. These signals are undesirable as they may interfere with other components or may exceed federally regulated levels.
IC package shield systems and packages including shields have found use in these applications, in order to inhibit the interference signals from entering or exiting the IC package. Conventional shields include a metallic cap which is adhered to the outside of IC package in order to cover the package. While the incorporation of such a cap is generally satisfactory for shielding the IC package, there is an associated increase in the size of the package, resulting in a disadvantageous increase in required motherboard area when assembled with a motherboard.
It is therefore an object of an aspect of the present invention to provide a ball grid array package with enhanced shielding properties to obviate or mitigate at least some of the disadvantages of the prior art.
In one aspect of the present invention, there is provided an integrated circuit package. The package has a substrate having first and second surfaces and a plurality of conductive traces therebetween. A stacked semiconductor die apparatus is coupled to the substrate. The stacked semiconductor die apparatus includes a first semiconductor die, a second semiconductor die stacked on the first semiconductor die and a shield disposed between the first and second semiconductor dice. A plurality of wire bonds connect the first and second semiconductor dice to ones of the conductive traces of the substrate. At least one encapsulating material encapsulates the wire bonds, the first semiconductor die and the second semiconductor die. A ball grid array is disposed on the second surface of the substrate such that bumps of the ball grid array are in electrical connection with ones of the conductive traces.
Advantageously, the shield is integrated into the package for shielding radio frequency interference signals or electromagnetic interference signals to or from the first semiconductor die. A relatively low profile shielded package is thereby provided. Also, since the shield is made, at least partly, of a metal, thermal dissipation is improved in the package.
In one particular embodiment, the shield is a substrate material, referred to as a second substrate, with circuitry and a metal plane on a backside thereof. The metal plane provides shielding while the circuitry allows further routing, lending to the flexibility of the package design. Also, the second substrate can be electrically connected to the bottom substrate. In another embodiment, passive components are integrated into the package.